New Polyketides from the Marine-Derived Fungus Letendraea sp. 5XNZ4-2

Marine-derived fungi have been reported to have great potential to produce structurally unique metabolites. Our investigation on secondary metabolites from marine-derived fungi resulted in the isolation of seven new polyketides (phomopsiketones D-G (1-4) and letendronols A-C (5-7)) as well as one known xylarinol (8) in the cultural broth of Letendraea sp. Their structures and absolute configurations were elucidated using a set of spectroscopic and chemical methods, including HRESIMS, NMR, single-crystal X-ray diffraction, ECD calculation, and a modified version of Mosher's method. Compound 2 showed weak inhibition against nitric oxide production in lipopolysaccaride-activated macrophages with an IC₅₀ value of 86 μM.